The present invention relates to the electrical component chassis art and, in particular, to a radio chassis interconnect structure which provides mechanical and electrical interconnection between two electrical circuits.
Electrical component chassis are well known, especially in the radio construction art. Radio chassis adapted for two-way radios have presented conflicting problems to the chassis designer. The trend is to a smaller radio chassis. However this brings the two-way radio's transmitter and receiver closer together. The radio frequency (RF) signal from the transmitter, if allowed to couple into the receiver circuitry, may desensitize the receiver, or result in a spurious response therefrom, rendering the receiver useless for its intended purpose. The closer the proximity of the transmitter to receiver the more likely it becomes that intercoupling between the two will affect two-way operation.
In addition, RF signals from external sources, if allowed to couple into the receiver may similarly desensitize it, and if coupled into the transmitter may result in spurious transmitter outputs.
Quite often lines carrying audio and/or DC signals must interconnect the transmitter and receiver. If not properly shielded and filtered, these lines can pick up RF signals from the transmitter and couple them to the receiver circuitry, resulting in the aforementioned undesired receiver desensitization and spurious responses.
The heretofore best approach to isolating the transmitter from the receiver of a two-way radio station is illustrated in FIG. 1. There, a transmitter module 10 is shown containing a number of internal electrical components (generally indicated by numeral 12) and an external heat sink 14. Connections to and from the electrical components 12 of the transmitter module 10 are accomplished via an edge connector 16 containing a number of metallized fingers, one of which is indicated at 18. Each finger 18 of the edge connector 16 is intended to couple either an audio frequency signal or a DC signal to or from the module 10. To prevent the strong RF signal generated by the transmitter for coupling to each of the output fingers 18 and thus possibly to the associated receiver module (not shown) a cover plate 20, having a filter housing 22 thereon is affixed via a plurality of screws over the electrical components 12 of the transmitter module 10. Contained within the housing 22 is an edge connector socket adapted to receive and connect to each electrical finger 18. Mounted to one edge of the housing 22 is a plurality of pi-section low pass filters, each filter 24 being comprised of a pair of feed through capacitors 26, 28 which are intercoupled by a series inductor 30. Each low pass filter 24 has selective component values to pass only audio and DC frequencies, thus filtering out undesired RF signals. The filters intercouple each finger 18 from the transmitter module 10 to a corresponding finger 32 which extends from the housing 22 for external connection to subsequent radio modules. A cover 40 secures to the housing 22 via a plurality of screws. The cover 40 mechanically protects and electrically shields the components of the low pass filters.
Subsequent radio modules, such as the receiver module, could electrically connect to each housing 22 finger 32 for receiving or sending the RF free audio or DC signal thereon.
This prior art two-way radio station has been costly to manufacture as well as being bulky in use due largely to the housing 22 which contains the low pass filter components. A substantial savings in manufacturing cost as well as in valuable space would be realized if the interconnecting structure between two or more modules could be accomplished without the use of the bulky filter housing.